Enhancing the efficiency of oscillating water column wave energy converters with sawtooth-shaped front walls: An experimental investigation

Numerous optimization studies on oscillating water column (OWC) wave energy converters have predominantly concentrated on designing streamlined front walls aimed at minimizing flow separation and energy dissipation. This study proposes an innovative strategy grounded in vortex dynamics that utilizes sawtooth-shaped front walls to intentionally induce flow nonuniformity, thus suppressing vortex formation and mitigating its adverse effects on energy conversion. Experimental investigations were conducted with the spacing and height of sawtooth structures as variables under various wave period conditions and power take-off (PTO) damping. The results reveal effective optimization outcomes and provide insights into the underlying flow mechanisms. Specifically, the optimal sawtooth configuration enhanced the wave energy conversion coefficient of the OWC by 10–25% across a broad range of wave frequencies and PTO conditions, and by as much as 30–40% under high-frequency wave scenarios when compared to conventional designs. The sawtooth-shaped front wall may mitigate large-scale vortex formation, thereby reducing hydrodynamic resistance and energy dissipation through the induction of flow nonuniformity. Moreover, under high-frequency wave conditions, the shallower flow channels resulting from the sawtooth configuration further facilitate energy capture. Furthermore, the optimization effects are highly sensitive to the geometric parameters, i.e., spacing and height of the sawtooth elements, which may correlate with the three-dimensional characteristics of vortex structures. These findings underscore the need for further research into the complex flow fields of OWCs, with a particular emphasis on vortex dynamics, to advance the design of sawtooth-based optimization strategies.